/*
** $Id: lapi.c,v 2.259 2016/02/29 14:27:14 roberto Exp $
** Lua API
** See Copyright Notice in lua.h
*/

#define lapi_c
#define LUA_CORE

#include "lprefix.h"


#include <stdarg.h>
#include <string.h>

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lundump.h"
#include "lvm.h"



const char lua_ident[] =
    "$LuaVersion: " LUA_COPYRIGHT " $"
    "$LuaAuthors: " LUA_AUTHORS " $";


/* value at a non-valid index */
#define NONVALIDVALUE       cast(TValue *, luaO_nilobject)

/* corresponding test */
#define isvalid(o)  ((o) != luaO_nilobject)

/* test for pseudo index */
#define ispseudo(i)     ((i) <= LUA_REGISTRYINDEX)

/* test for upvalue */
#define isupvalue(i)        ((i) < LUA_REGISTRYINDEX)

/* test for valid but not pseudo index */
#define isstackindex(i, o)  (isvalid(o) && !ispseudo(i))

#define api_checkvalidindex(l,o)  api_check(l, isvalid(o), "invalid index")

#define api_checkstackindex(l, i, o)  \
    api_check(l, isstackindex(i, o), "index not in the stack")


static TValue *index2addr(lua_State *L, int idx)
{
    CallInfo *ci = L->ci;
    if (idx > 0)
    {
        TValue *o = ci->func + idx;
        api_check(L, idx <= ci->top - (ci->func + 1), "unacceptable index");
        if (o >= L->top) return NONVALIDVALUE;
        else return o;
    }
    else if (!ispseudo(idx))    /* negative index */
    {
        api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
        return L->top + idx;
    }
    else if (idx == LUA_REGISTRYINDEX)
        return &G(L)->l_registry;
    else    /* upvalues */
    {
        idx = LUA_REGISTRYINDEX - idx;
        api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large");
        if (ttislcf(ci->func))  /* light C function? */
            return NONVALIDVALUE;  /* it has no upvalues */
        else
        {
            CClosure *func = clCvalue(ci->func);
            return (idx <= func->nupvalues) ? &func->upvalue[idx - 1] : NONVALIDVALUE;
        }
    }
}


/*
** to be called by 'lua_checkstack' in protected mode, to grow stack
** capturing memory errors
*/
static void growstack(lua_State *L, void *ud)
{
    int size = *(int *)ud;
    luaD_growstack(L, size);
}


LUA_API int lua_checkstack(lua_State *L, int n)
{
    int res;
    CallInfo *ci = L->ci;
    lua_lock(L);
    api_check(L, n >= 0, "negative 'n'");
    if (L->stack_last - L->top > n)  /* stack large enough? */
        res = 1;  /* yes; check is OK */
    else    /* no; need to grow stack */
    {
        int inuse = cast_int(L->top - L->stack) + EXTRA_STACK;
        if (inuse > LUAI_MAXSTACK - n)  /* can grow without overflow? */
            res = 0;  /* no */
        else  /* try to grow stack */
            res = (luaD_rawrunprotected(L, &growstack, &n) == LUA_OK);
    }
    if (res && ci->top < L->top + n)
        ci->top = L->top + n;  /* adjust frame top */
    lua_unlock(L);
    return res;
}


LUA_API void lua_xmove(lua_State *from, lua_State *to, int n)
{
    int i;
    if (from == to) return;
    lua_lock(to);
    api_checknelems(from, n);
    api_check(from, G(from) == G(to), "moving among independent states");
    api_check(from, to->ci->top - to->top >= n, "stack overflow");
    from->top -= n;
    for (i = 0; i < n; i++)
    {
        setobj2s(to, to->top, from->top + i);
        to->top++;  /* stack already checked by previous 'api_check' */
    }
    lua_unlock(to);
}


LUA_API lua_CFunction lua_atpanic(lua_State *L, lua_CFunction panicf)
{
    lua_CFunction old;
    lua_lock(L);
    old = G(L)->panic;
    G(L)->panic = panicf;
    lua_unlock(L);
    return old;
}


LUA_API const lua_Number *lua_version(lua_State *L)
{
    static const lua_Number version = LUA_VERSION_NUM;
    if (L == NULL) return &version;
    else return G(L)->version;
}



/*
** basic stack manipulation
*/


/*
** convert an acceptable stack index into an absolute index
*/
LUA_API int lua_absindex(lua_State *L, int idx)
{
    return (idx > 0 || ispseudo(idx))
           ? idx
           : cast_int(L->top - L->ci->func) + idx;
}


LUA_API int lua_gettop(lua_State *L)
{
    return cast_int(L->top - (L->ci->func + 1));
}


LUA_API void lua_settop(lua_State *L, int idx)
{
    StkId func = L->ci->func;
    lua_lock(L);
    if (idx >= 0)
    {
        api_check(L, idx <= L->stack_last - (func + 1), "new top too large");
        while (L->top < (func + 1) + idx)
            setnilvalue(L->top++);
        L->top = (func + 1) + idx;
    }
    else
    {
        api_check(L, -(idx + 1) <= (L->top - (func + 1)), "invalid new top");
        L->top += idx + 1; /* 'subtract' index (index is negative) */
    }
    lua_unlock(L);
}


/*
** Reverse the stack segment from 'from' to 'to'
** (auxiliary to 'lua_rotate')
*/
static void reverse(lua_State *L, StkId from, StkId to)
{
    for (; from < to; from++, to--)
    {
        TValue temp;
        setobj(L, &temp, from);
        setobjs2s(L, from, to);
        setobj2s(L, to, &temp);
    }
}


/*
** Let x = AB, where A is a prefix of length 'n'. Then,
** rotate x n == BA. But BA == (A^r . B^r)^r.
*/
LUA_API void lua_rotate(lua_State *L, int idx, int n)
{
    StkId p, t, m;
    lua_lock(L);
    t = L->top - 1;  /* end of stack segment being rotated */
    p = index2addr(L, idx);  /* start of segment */
    api_checkstackindex(L, idx, p);
    api_check(L, (n >= 0 ? n : -n) <= (t - p + 1), "invalid 'n'");
    m = (n >= 0 ? t - n : p - n - 1);  /* end of prefix */
    reverse(L, p, m);  /* reverse the prefix with length 'n' */
    reverse(L, m + 1, t);  /* reverse the suffix */
    reverse(L, p, t);  /* reverse the entire segment */
    lua_unlock(L);
}


LUA_API void lua_copy(lua_State *L, int fromidx, int toidx)
{
    TValue *fr, *to;
    lua_lock(L);
    fr = index2addr(L, fromidx);
    to = index2addr(L, toidx);
    api_checkvalidindex(L, to);
    setobj(L, to, fr);
    if (isupvalue(toidx))  /* function upvalue? */
        luaC_barrier(L, clCvalue(L->ci->func), fr);
    /* LUA_REGISTRYINDEX does not need gc barrier
       (collector revisits it before finishing collection) */
    lua_unlock(L);
}


LUA_API void lua_pushvalue(lua_State *L, int idx)
{
    lua_lock(L);
    setobj2s(L, L->top, index2addr(L, idx));
    api_incr_top(L);
    lua_unlock(L);
}



/*
** access functions (stack -> C)
*/


LUA_API int lua_type(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    return (isvalid(o) ? ttnov(o) : LUA_TNONE);
}


LUA_API const char *lua_typename(lua_State *L, int t)
{
    UNUSED(L);
    api_check(L, LUA_TNONE <= t && t < LUA_NUMTAGS, "invalid tag");
    return ttypename(t);
}


LUA_API int lua_iscfunction(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    return (ttislcf(o) || (ttisCclosure(o)));
}


LUA_API int lua_isinteger(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    return ttisinteger(o);
}


LUA_API int lua_isnumber(lua_State *L, int idx)
{
    lua_Number n;
    const TValue *o = index2addr(L, idx);
    return tonumber(o, &n);
}


LUA_API int lua_isstring(lua_State *L, int idx)
{
    const TValue *o = index2addr(L, idx);
    return (ttisstring(o) || cvt2str(o));
}


LUA_API int lua_isuserdata(lua_State *L, int idx)
{
    const TValue *o = index2addr(L, idx);
    return (ttisfulluserdata(o) || ttislightuserdata(o));
}


LUA_API int lua_rawequal(lua_State *L, int index1, int index2)
{
    StkId o1 = index2addr(L, index1);
    StkId o2 = index2addr(L, index2);
    return (isvalid(o1) && isvalid(o2)) ? luaV_rawequalobj(o1, o2) : 0;
}


LUA_API void lua_arith(lua_State *L, int op)
{
    lua_lock(L);
    if (op != LUA_OPUNM && op != LUA_OPBNOT)
        api_checknelems(L, 2);  /* all other operations expect two operands */
    else    /* for unary operations, add fake 2nd operand */
    {
        api_checknelems(L, 1);
        setobjs2s(L, L->top, L->top - 1);
        api_incr_top(L);
    }
    /* first operand at top - 2, second at top - 1; result go to top - 2 */
    luaO_arith(L, op, L->top - 2, L->top - 1, L->top - 2);
    L->top--;  /* remove second operand */
    lua_unlock(L);
}


LUA_API int lua_compare(lua_State *L, int index1, int index2, int op)
{
    StkId o1, o2;
    int i = 0;
    lua_lock(L);  /* may call tag method */
    o1 = index2addr(L, index1);
    o2 = index2addr(L, index2);
    if (isvalid(o1) && isvalid(o2))
    {
        switch (op)
        {
        case LUA_OPEQ:
            i = luaV_equalobj(L, o1, o2);
            break;
        case LUA_OPLT:
            i = luaV_lessthan(L, o1, o2);
            break;
        case LUA_OPLE:
            i = luaV_lessequal(L, o1, o2);
            break;
        default:
            api_check(L, 0, "invalid option");
        }
    }
    lua_unlock(L);
    return i;
}


LUA_API size_t lua_stringtonumber(lua_State *L, const char *s)
{
    size_t sz = luaO_str2num(s, L->top);
    if (sz != 0)
        api_incr_top(L);
    return sz;
}


LUA_API lua_Number lua_tonumberx(lua_State *L, int idx, int *pisnum)
{
    lua_Number n;
    const TValue *o = index2addr(L, idx);
    int isnum = tonumber(o, &n);
    if (!isnum)
        n = 0;  /* call to 'tonumber' may change 'n' even if it fails */
    if (pisnum) *pisnum = isnum;
    return n;
}


LUA_API lua_Integer lua_tointegerx(lua_State *L, int idx, int *pisnum)
{
    lua_Integer res;
    const TValue *o = index2addr(L, idx);
    int isnum = tointeger(o, &res);
    if (!isnum)
        res = 0;  /* call to 'tointeger' may change 'n' even if it fails */
    if (pisnum) *pisnum = isnum;
    return res;
}


LUA_API int lua_toboolean(lua_State *L, int idx)
{
    const TValue *o = index2addr(L, idx);
    return !l_isfalse(o);
}


LUA_API const char *lua_tolstring(lua_State *L, int idx, size_t *len)
{
    StkId o = index2addr(L, idx);
    if (!ttisstring(o))
    {
        if (!cvt2str(o))    /* not convertible? */
        {
            if (len != NULL) *len = 0;
            return NULL;
        }
        lua_lock(L);  /* 'luaO_tostring' may create a new string */
        luaO_tostring(L, o);
        luaC_checkGC(L);
        o = index2addr(L, idx);  /* previous call may reallocate the stack */
        lua_unlock(L);
    }
    if (len != NULL)
        *len = vslen(o);
    return svalue(o);
}


LUA_API size_t lua_rawlen(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    switch (ttype(o))
    {
    case LUA_TSHRSTR:
        return tsvalue(o)->shrlen;
    case LUA_TLNGSTR:
        return tsvalue(o)->u.lnglen;
    case LUA_TUSERDATA:
        return uvalue(o)->len;
    case LUA_TTABLE:
        return luaH_getn(hvalue(o));
    default:
        return 0;
    }
}


LUA_API lua_CFunction lua_tocfunction(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    if (ttislcf(o)) return fvalue(o);
    else if (ttisCclosure(o))
        return clCvalue(o)->f;
    else return NULL;  /* not a C function */
}


LUA_API void *lua_touserdata(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    switch (ttnov(o))
    {
    case LUA_TUSERDATA:
        return getudatamem(uvalue(o));
    case LUA_TLIGHTUSERDATA:
        return pvalue(o);
    default:
        return NULL;
    }
}


LUA_API lua_State *lua_tothread(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    return (!ttisthread(o)) ? NULL : thvalue(o);
}


LUA_API const void *lua_topointer(lua_State *L, int idx)
{
    StkId o = index2addr(L, idx);
    switch (ttype(o))
    {
    case LUA_TTABLE:
        return hvalue(o);
    case LUA_TLCL:
        return clLvalue(o);
    case LUA_TCCL:
        return clCvalue(o);
    case LUA_TLCF:
        return cast(void *, cast(size_t, fvalue(o)));
    case LUA_TTHREAD:
        return thvalue(o);
    case LUA_TUSERDATA:
        return getudatamem(uvalue(o));
    case LUA_TLIGHTUSERDATA:
        return pvalue(o);
    default:
        return NULL;
    }
}



/*
** push functions (C -> stack)
*/


LUA_API void lua_pushnil(lua_State *L)
{
    lua_lock(L);
    setnilvalue(L->top);
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API void lua_pushnumber(lua_State *L, lua_Number n)
{
    lua_lock(L);
    setfltvalue(L->top, n);
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API void lua_pushinteger(lua_State *L, lua_Integer n)
{
    lua_lock(L);
    setivalue(L->top, n);
    api_incr_top(L);
    lua_unlock(L);
}


/*
** Pushes on the stack a string with given length. Avoid using 's' when
** 'len' == 0 (as 's' can be NULL in that case), due to later use of
** 'memcmp' and 'memcpy'.
*/
LUA_API const char *lua_pushlstring(lua_State *L, const char *s, size_t len)
{
    TString *ts;
    lua_lock(L);
    ts = (len == 0) ? luaS_new(L, "") : luaS_newlstr(L, s, len);
    setsvalue2s(L, L->top, ts);
    api_incr_top(L);
    luaC_checkGC(L);
    lua_unlock(L);
    return getstr(ts);
}


LUA_API const char *lua_pushstring(lua_State *L, const char *s)
{
    lua_lock(L);
    if (s == NULL)
        setnilvalue(L->top);
    else
    {
        TString *ts;
        ts = luaS_new(L, s);
        setsvalue2s(L, L->top, ts);
        s = getstr(ts);  /* internal copy's address */
    }
    api_incr_top(L);
    luaC_checkGC(L);
    lua_unlock(L);
    return s;
}


LUA_API const char *lua_pushvfstring(lua_State *L, const char *fmt,
                                     va_list argp)
{
    const char *ret;
    lua_lock(L);
    ret = luaO_pushvfstring(L, fmt, argp);
    luaC_checkGC(L);
    lua_unlock(L);
    return ret;
}


LUA_API const char *lua_pushfstring(lua_State *L, const char *fmt, ...)
{
    const char *ret;
    va_list argp;
    lua_lock(L);
    va_start(argp, fmt);
    ret = luaO_pushvfstring(L, fmt, argp);
    va_end(argp);
    luaC_checkGC(L);
    lua_unlock(L);
    return ret;
}


LUA_API void lua_pushcclosure(lua_State *L, lua_CFunction fn, int n)
{
    lua_lock(L);
    if (n == 0)
    {
        setfvalue(L->top, fn);
    }
    else
    {
        CClosure *cl;
        api_checknelems(L, n);
        api_check(L, n <= MAXUPVAL, "upvalue index too large");
        cl = luaF_newCclosure(L, n);
        cl->f = fn;
        L->top -= n;
        while (n--)
        {
            setobj2n(L, &cl->upvalue[n], L->top + n);
            /* does not need barrier because closure is white */
        }
        setclCvalue(L, L->top, cl);
    }
    api_incr_top(L);
    luaC_checkGC(L);
    lua_unlock(L);
}


LUA_API void lua_pushboolean(lua_State *L, int b)
{
    lua_lock(L);
    setbvalue(L->top, (b != 0));  /* ensure that true is 1 */
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API void lua_pushlightuserdata(lua_State *L, void *p)
{
    lua_lock(L);
    setpvalue(L->top, p);
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API int lua_pushthread(lua_State *L)
{
    lua_lock(L);
    setthvalue(L, L->top, L);
    api_incr_top(L);
    lua_unlock(L);
    return (G(L)->mainthread == L);
}



/*
** get functions (Lua -> stack)
*/


static int auxgetstr(lua_State *L, const TValue *t, const char *k)
{
    const TValue *slot;
    TString *str = luaS_new(L, k);
    if (luaV_fastget(L, t, str, slot, luaH_getstr))
    {
        setobj2s(L, L->top, slot);
        api_incr_top(L);
    }
    else
    {
        setsvalue2s(L, L->top, str);
        api_incr_top(L);
        luaV_finishget(L, t, L->top - 1, L->top - 1, slot);
    }
    lua_unlock(L);
    return ttnov(L->top - 1);
}


LUA_API int lua_getglobal(lua_State *L, const char *name)
{
    Table *reg = hvalue(&G(L)->l_registry);
    lua_lock(L);
    return auxgetstr(L, luaH_getint(reg, LUA_RIDX_GLOBALS), name);
}


LUA_API int lua_gettable(lua_State *L, int idx)
{
    StkId t;
    lua_lock(L);
    t = index2addr(L, idx);
    luaV_gettable(L, t, L->top - 1, L->top - 1);
    lua_unlock(L);
    return ttnov(L->top - 1);
}


LUA_API int lua_getfield(lua_State *L, int idx, const char *k)
{
    lua_lock(L);
    return auxgetstr(L, index2addr(L, idx), k);
}


LUA_API int lua_geti(lua_State *L, int idx, lua_Integer n)
{
    StkId t;
    const TValue *slot;
    lua_lock(L);
    t = index2addr(L, idx);
    if (luaV_fastget(L, t, n, slot, luaH_getint))
    {
        setobj2s(L, L->top, slot);
        api_incr_top(L);
    }
    else
    {
        setivalue(L->top, n);
        api_incr_top(L);
        luaV_finishget(L, t, L->top - 1, L->top - 1, slot);
    }
    lua_unlock(L);
    return ttnov(L->top - 1);
}


LUA_API int lua_rawget(lua_State *L, int idx)
{
    StkId t;
    lua_lock(L);
    t = index2addr(L, idx);
    api_check(L, ttistable(t), "table expected");
    setobj2s(L, L->top - 1, luaH_get(hvalue(t), L->top - 1));
    lua_unlock(L);
    return ttnov(L->top - 1);
}


LUA_API int lua_rawgeti(lua_State *L, int idx, lua_Integer n)
{
    StkId t;
    lua_lock(L);
    t = index2addr(L, idx);
    api_check(L, ttistable(t), "table expected");
    setobj2s(L, L->top, luaH_getint(hvalue(t), n));
    api_incr_top(L);
    lua_unlock(L);
    return ttnov(L->top - 1);
}


LUA_API int lua_rawgetp(lua_State *L, int idx, const void *p)
{
    StkId t;
    TValue k;
    lua_lock(L);
    t = index2addr(L, idx);
    api_check(L, ttistable(t), "table expected");
    setpvalue(&k, cast(void *, p));
    setobj2s(L, L->top, luaH_get(hvalue(t), &k));
    api_incr_top(L);
    lua_unlock(L);
    return ttnov(L->top - 1);
}


LUA_API void lua_createtable(lua_State *L, int narray, int nrec)
{
    Table *t;
    lua_lock(L);
    t = luaH_new(L);
    sethvalue(L, L->top, t);
    api_incr_top(L);
    if (narray > 0 || nrec > 0)
        luaH_resize(L, t, narray, nrec);
    luaC_checkGC(L);
    lua_unlock(L);
}


LUA_API int lua_getmetatable(lua_State *L, int objindex)
{
    const TValue *obj;
    Table *mt;
    int res = 0;
    lua_lock(L);
    obj = index2addr(L, objindex);
    switch (ttnov(obj))
    {
    case LUA_TTABLE:
        mt = hvalue(obj)->metatable;
        break;
    case LUA_TUSERDATA:
        mt = uvalue(obj)->metatable;
        break;
    default:
        mt = G(L)->mt[ttnov(obj)];
        break;
    }
    if (mt != NULL)
    {
        sethvalue(L, L->top, mt);
        api_incr_top(L);
        res = 1;
    }
    lua_unlock(L);
    return res;
}


LUA_API int lua_getuservalue(lua_State *L, int idx)
{
    StkId o;
    lua_lock(L);
    o = index2addr(L, idx);
    api_check(L, ttisfulluserdata(o), "full userdata expected");
    getuservalue(L, uvalue(o), L->top);
    api_incr_top(L);
    lua_unlock(L);
    return ttnov(L->top - 1);
}


/*
** set functions (stack -> Lua)
*/

/*
** t[k] = value at the top of the stack (where 'k' is a string)
*/
static void auxsetstr(lua_State *L, const TValue *t, const char *k)
{
    const TValue *slot;
    TString *str = luaS_new(L, k);
    api_checknelems(L, 1);
    if (luaV_fastset(L, t, str, slot, luaH_getstr, L->top - 1))
        L->top--;  /* pop value */
    else
    {
        setsvalue2s(L, L->top, str);  /* push 'str' (to make it a TValue) */
        api_incr_top(L);
        luaV_finishset(L, t, L->top - 1, L->top - 2, slot);
        L->top -= 2;  /* pop value and key */
    }
    lua_unlock(L);  /* lock done by caller */
}


LUA_API void lua_setglobal(lua_State *L, const char *name)
{
    Table *reg = hvalue(&G(L)->l_registry);
    lua_lock(L);  /* unlock done in 'auxsetstr' */
    auxsetstr(L, luaH_getint(reg, LUA_RIDX_GLOBALS), name);
}


LUA_API void lua_settable(lua_State *L, int idx)
{
    StkId t;
    lua_lock(L);
    api_checknelems(L, 2);
    t = index2addr(L, idx);
    luaV_settable(L, t, L->top - 2, L->top - 1);
    L->top -= 2;  /* pop index and value */
    lua_unlock(L);
}


LUA_API void lua_setfield(lua_State *L, int idx, const char *k)
{
    lua_lock(L);  /* unlock done in 'auxsetstr' */
    auxsetstr(L, index2addr(L, idx), k);
}


LUA_API void lua_seti(lua_State *L, int idx, lua_Integer n)
{
    StkId t;
    const TValue *slot;
    lua_lock(L);
    api_checknelems(L, 1);
    t = index2addr(L, idx);
    if (luaV_fastset(L, t, n, slot, luaH_getint, L->top - 1))
        L->top--;  /* pop value */
    else
    {
        setivalue(L->top, n);
        api_incr_top(L);
        luaV_finishset(L, t, L->top - 1, L->top - 2, slot);
        L->top -= 2;  /* pop value and key */
    }
    lua_unlock(L);
}


LUA_API void lua_rawset(lua_State *L, int idx)
{
    StkId o;
    TValue *slot;
    lua_lock(L);
    api_checknelems(L, 2);
    o = index2addr(L, idx);
    api_check(L, ttistable(o), "table expected");
    slot = luaH_set(L, hvalue(o), L->top - 2);
    setobj2t(L, slot, L->top - 1);
    invalidateTMcache(hvalue(o));
    luaC_barrierback(L, hvalue(o), L->top - 1);
    L->top -= 2;
    lua_unlock(L);
}


LUA_API void lua_rawseti(lua_State *L, int idx, lua_Integer n)
{
    StkId o;
    lua_lock(L);
    api_checknelems(L, 1);
    o = index2addr(L, idx);
    api_check(L, ttistable(o), "table expected");
    luaH_setint(L, hvalue(o), n, L->top - 1);
    luaC_barrierback(L, hvalue(o), L->top - 1);
    L->top--;
    lua_unlock(L);
}


LUA_API void lua_rawsetp(lua_State *L, int idx, const void *p)
{
    StkId o;
    TValue k, *slot;
    lua_lock(L);
    api_checknelems(L, 1);
    o = index2addr(L, idx);
    api_check(L, ttistable(o), "table expected");
    setpvalue(&k, cast(void *, p));
    slot = luaH_set(L, hvalue(o), &k);
    setobj2t(L, slot, L->top - 1);
    luaC_barrierback(L, hvalue(o), L->top - 1);
    L->top--;
    lua_unlock(L);
}


LUA_API int lua_setmetatable(lua_State *L, int objindex)
{
    TValue *obj;
    Table *mt;
    lua_lock(L);
    api_checknelems(L, 1);
    obj = index2addr(L, objindex);
    if (ttisnil(L->top - 1))
        mt = NULL;
    else
    {
        api_check(L, ttistable(L->top - 1), "table expected");
        mt = hvalue(L->top - 1);
    }
    switch (ttnov(obj))
    {
    case LUA_TTABLE:
    {
        hvalue(obj)->metatable = mt;
        if (mt)
        {
            luaC_objbarrier(L, gcvalue(obj), mt);
            luaC_checkfinalizer(L, gcvalue(obj), mt);
        }
        break;
    }
    case LUA_TUSERDATA:
    {
        uvalue(obj)->metatable = mt;
        if (mt)
        {
            luaC_objbarrier(L, uvalue(obj), mt);
            luaC_checkfinalizer(L, gcvalue(obj), mt);
        }
        break;
    }
    default:
    {
        G(L)->mt[ttnov(obj)] = mt;
        break;
    }
    }
    L->top--;
    lua_unlock(L);
    return 1;
}


LUA_API void lua_setuservalue(lua_State *L, int idx)
{
    StkId o;
    lua_lock(L);
    api_checknelems(L, 1);
    o = index2addr(L, idx);
    api_check(L, ttisfulluserdata(o), "full userdata expected");
    setuservalue(L, uvalue(o), L->top - 1);
    luaC_barrier(L, gcvalue(o), L->top - 1);
    L->top--;
    lua_unlock(L);
}


/*
** 'load' and 'call' functions (run Lua code)
*/


#define checkresults(L,na,nr) \
     api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)), \
    "results from function overflow current stack size")


LUA_API void lua_callk(lua_State *L, int nargs, int nresults,
                       lua_KContext ctx, lua_KFunction k)
{
    StkId func;
    lua_lock(L);
    api_check(L, k == NULL || !isLua(L->ci),
              "cannot use continuations inside hooks");
    api_checknelems(L, nargs + 1);
    api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
    checkresults(L, nargs, nresults);
    func = L->top - (nargs + 1);
    if (k != NULL && L->nny == 0)    /* need to prepare continuation? */
    {
        L->ci->u.c.k = k;  /* save continuation */
        L->ci->u.c.ctx = ctx;  /* save context */
        luaD_call(L, func, nresults);  /* do the call */
    }
    else  /* no continuation or no yieldable */
        luaD_callnoyield(L, func, nresults);  /* just do the call */
    adjustresults(L, nresults);
    lua_unlock(L);
}



/*
** Execute a protected call.
*/
struct CallS    /* data to 'f_call' */
{
    StkId func;
    int nresults;
};


static void f_call(lua_State *L, void *ud)
{
    struct CallS *c = cast(struct CallS *, ud);
    luaD_callnoyield(L, c->func, c->nresults);
}



LUA_API int lua_pcallk(lua_State *L, int nargs, int nresults, int errfunc,
                       lua_KContext ctx, lua_KFunction k)
{
    struct CallS c;
    int status;
    ptrdiff_t func;
    lua_lock(L);
    api_check(L, k == NULL || !isLua(L->ci),
              "cannot use continuations inside hooks");
    api_checknelems(L, nargs + 1);
    api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
    checkresults(L, nargs, nresults);
    if (errfunc == 0)
        func = 0;
    else
    {
        StkId o = index2addr(L, errfunc);
        api_checkstackindex(L, errfunc, o);
        func = savestack(L, o);
    }
    c.func = L->top - (nargs + 1); /* function to be called */
    if (k == NULL || L->nny > 0)    /* no continuation or no yieldable? */
    {
        c.nresults = nresults;  /* do a 'conventional' protected call */
        status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func);
    }
    else    /* prepare continuation (call is already protected by 'resume') */
    {
        CallInfo *ci = L->ci;
        ci->u.c.k = k;  /* save continuation */
        ci->u.c.ctx = ctx;  /* save context */
        /* save information for error recovery */
        ci->extra = savestack(L, c.func);
        ci->u.c.old_errfunc = L->errfunc;
        L->errfunc = func;
        setoah(ci->callstatus, L->allowhook);  /* save value of 'allowhook' */
        ci->callstatus |= CIST_YPCALL;  /* function can do error recovery */
        luaD_call(L, c.func, nresults);  /* do the call */
        ci->callstatus &= ~CIST_YPCALL;
        L->errfunc = ci->u.c.old_errfunc;
        status = LUA_OK;  /* if it is here, there were no errors */
    }
    adjustresults(L, nresults);
    lua_unlock(L);
    return status;
}


LUA_API int lua_load(lua_State *L, lua_Reader reader, void *data,
                     const char *chunkname, const char *mode)
{
    ZIO z;
    int status;
    lua_lock(L);
    if (!chunkname) chunkname = "?";
    luaZ_init(L, &z, reader, data);
    status = luaD_protectedparser(L, &z, chunkname, mode);
    if (status == LUA_OK)    /* no errors? */
    {
        LClosure *f = clLvalue(L->top - 1);  /* get newly created function */
        if (f->nupvalues >= 1)    /* does it have an upvalue? */
        {
            /* get global table from registry */
            Table *reg = hvalue(&G(L)->l_registry);
            const TValue *gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
            /* set global table as 1st upvalue of 'f' (may be LUA_ENV) */
            setobj(L, f->upvals[0]->v, gt);
            luaC_upvalbarrier(L, f->upvals[0]);
        }
    }
    lua_unlock(L);
    return status;
}


LUA_API int lua_dump(lua_State *L, lua_Writer writer, void *data, int strip)
{
    int status;
    TValue *o;
    lua_lock(L);
    api_checknelems(L, 1);
    o = L->top - 1;
    if (isLfunction(o))
        status = luaU_dump(L, getproto(o), writer, data, strip);
    else
        status = 1;
    lua_unlock(L);
    return status;
}


LUA_API int lua_status(lua_State *L)
{
    return L->status;
}


/*
** Garbage-collection function
*/

LUA_API int lua_gc(lua_State *L, int what, int data)
{
    int res = 0;
    global_State *g;
    lua_lock(L);
    g = G(L);
    switch (what)
    {
    case LUA_GCSTOP:
    {
        g->gcrunning = 0;
        break;
    }
    case LUA_GCRESTART:
    {
        luaE_setdebt(g, 0);
        g->gcrunning = 1;
        break;
    }
    case LUA_GCCOLLECT:
    {
        luaC_fullgc(L, 0);
        break;
    }
    case LUA_GCCOUNT:
    {
        /* GC values are expressed in Kbytes: #bytes/2^10 */
        res = cast_int(gettotalbytes(g) >> 10);
        break;
    }
    case LUA_GCCOUNTB:
    {
        res = cast_int(gettotalbytes(g) & 0x3ff);
        break;
    }
    case LUA_GCSTEP:
    {
        l_mem debt = 1;  /* =1 to signal that it did an actual step */
        lu_byte oldrunning = g->gcrunning;
        g->gcrunning = 1;  /* allow GC to run */
        if (data == 0)
        {
            luaE_setdebt(g, -GCSTEPSIZE);  /* to do a "small" step */
            luaC_step(L);
        }
        else    /* add 'data' to total debt */
        {
            debt = cast(l_mem, data) * 1024 + g->GCdebt;
            luaE_setdebt(g, debt);
            luaC_checkGC(L);
        }
        g->gcrunning = oldrunning;  /* restore previous state */
        if (debt > 0 && g->gcstate == GCSpause)  /* end of cycle? */
            res = 1;  /* signal it */
        break;
    }
    case LUA_GCSETPAUSE:
    {
        res = g->gcpause;
        g->gcpause = data;
        break;
    }
    case LUA_GCSETSTEPMUL:
    {
        res = g->gcstepmul;
        if (data < 40) data = 40;  /* avoid ridiculous low values (and 0) */
        g->gcstepmul = data;
        break;
    }
    case LUA_GCISRUNNING:
    {
        res = g->gcrunning;
        break;
    }
    default:
        res = -1;  /* invalid option */
    }
    lua_unlock(L);
    return res;
}



/*
** miscellaneous functions
*/


LUA_API int lua_error(lua_State *L)
{
    lua_lock(L);
    api_checknelems(L, 1);
    luaG_errormsg(L);
    /* code unreachable; will unlock when control actually leaves the kernel */
    return 0;  /* to avoid warnings */
}


LUA_API int lua_next(lua_State *L, int idx)
{
    StkId t;
    int more;
    lua_lock(L);
    t = index2addr(L, idx);
    api_check(L, ttistable(t), "table expected");
    more = luaH_next(L, hvalue(t), L->top - 1);
    if (more)
    {
        api_incr_top(L);
    }
    else  /* no more elements */
        L->top -= 1;  /* remove key */
    lua_unlock(L);
    return more;
}


LUA_API void lua_concat(lua_State *L, int n)
{
    lua_lock(L);
    api_checknelems(L, n);
    if (n >= 2)
    {
        luaV_concat(L, n);
    }
    else if (n == 0)    /* push empty string */
    {
        setsvalue2s(L, L->top, luaS_newlstr(L, "", 0));
        api_incr_top(L);
    }
    /* else n == 1; nothing to do */
    luaC_checkGC(L);
    lua_unlock(L);
}


LUA_API void lua_len(lua_State *L, int idx)
{
    StkId t;
    lua_lock(L);
    t = index2addr(L, idx);
    luaV_objlen(L, L->top, t);
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API lua_Alloc lua_getallocf(lua_State *L, void **ud)
{
    lua_Alloc f;
    lua_lock(L);
    if (ud) *ud = G(L)->ud;
    f = G(L)->frealloc;
    lua_unlock(L);
    return f;
}


LUA_API void lua_setallocf(lua_State *L, lua_Alloc f, void *ud)
{
    lua_lock(L);
    G(L)->ud = ud;
    G(L)->frealloc = f;
    lua_unlock(L);
}


LUA_API void *lua_newuserdata(lua_State *L, size_t size)
{
    Udata *u;
    lua_lock(L);
    u = luaS_newudata(L, size);
    setuvalue(L, L->top, u);
    api_incr_top(L);
    luaC_checkGC(L);
    lua_unlock(L);
    return getudatamem(u);
}



static const char *aux_upvalue(StkId fi, int n, TValue **val,
                               CClosure **owner, UpVal **uv)
{
    switch (ttype(fi))
    {
    case LUA_TCCL:    /* C closure */
    {
        CClosure *f = clCvalue(fi);
        if (!(1 <= n && n <= f->nupvalues)) return NULL;
        *val = &f->upvalue[n - 1];
        if (owner) *owner = f;
        return "";
    }
    case LUA_TLCL:    /* Lua closure */
    {
        LClosure *f = clLvalue(fi);
        TString *name;
        Proto *p = f->p;
        if (!(1 <= n && n <= p->sizeupvalues)) return NULL;
        *val = f->upvals[n - 1]->v;
        if (uv) *uv = f->upvals[n - 1];
        name = p->upvalues[n - 1].name;
        return (name == NULL) ? "(*no name)" : getstr(name);
    }
    default:
        return NULL;  /* not a closure */
    }
}


LUA_API const char *lua_getupvalue(lua_State *L, int funcindex, int n)
{
    const char *name;
    TValue *val = NULL;  /* to avoid warnings */
    lua_lock(L);
    name = aux_upvalue(index2addr(L, funcindex), n, &val, NULL, NULL);
    if (name)
    {
        setobj2s(L, L->top, val);
        api_incr_top(L);
    }
    lua_unlock(L);
    return name;
}


LUA_API const char *lua_setupvalue(lua_State *L, int funcindex, int n)
{
    const char *name;
    TValue *val = NULL;  /* to avoid warnings */
    CClosure *owner = NULL;
    UpVal *uv = NULL;
    StkId fi;
    lua_lock(L);
    fi = index2addr(L, funcindex);
    api_checknelems(L, 1);
    name = aux_upvalue(fi, n, &val, &owner, &uv);
    if (name)
    {
        L->top--;
        setobj(L, val, L->top);
        if (owner)
        {
            luaC_barrier(L, owner, L->top);
        }
        else if (uv)
        {
            luaC_upvalbarrier(L, uv);
        }
    }
    lua_unlock(L);
    return name;
}


static UpVal **getupvalref(lua_State *L, int fidx, int n, LClosure **pf)
{
    LClosure *f;
    StkId fi = index2addr(L, fidx);
    api_check(L, ttisLclosure(fi), "Lua function expected");
    f = clLvalue(fi);
    api_check(L, (1 <= n && n <= f->p->sizeupvalues), "invalid upvalue index");
    if (pf) *pf = f;
    return &f->upvals[n - 1];  /* get its upvalue pointer */
}


LUA_API void *lua_upvalueid(lua_State *L, int fidx, int n)
{
    StkId fi = index2addr(L, fidx);
    switch (ttype(fi))
    {
    case LUA_TLCL:    /* lua closure */
    {
        return *getupvalref(L, fidx, n, NULL);
    }
    case LUA_TCCL:    /* C closure */
    {
        CClosure *f = clCvalue(fi);
        api_check(L, 1 <= n && n <= f->nupvalues, "invalid upvalue index");
        return &f->upvalue[n - 1];
    }
    default:
    {
        api_check(L, 0, "closure expected");
        return NULL;
    }
    }
}


LUA_API void lua_upvaluejoin(lua_State *L, int fidx1, int n1,
                             int fidx2, int n2)
{
    LClosure *f1;
    UpVal **up1 = getupvalref(L, fidx1, n1, &f1);
    UpVal **up2 = getupvalref(L, fidx2, n2, NULL);
    luaC_upvdeccount(L, *up1);
    *up1 = *up2;
    (*up1)->refcount++;
    if (upisopen(*up1))(*up1)->u.open.touched = 1;
    luaC_upvalbarrier(L, *up1);
}


